Machine gun jacket mounting



Dec. 14, 1937. 5, G GREEN MACHINE GUN JACKET MOUNTING Filed Nov. 20, 1936 l .9 /a lo Invantur' E a mu E]. [3. Green Att urn E Patented Dec. 14, 1937 1 UNITED ,STATES' PATENT O'FFICE" 2 Claims.

(Granted under the act of March 3, 1883,as

amended April 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a machinegun jacket mounting.

The purpose-of the invention is to provide a machine gun trunnion block which is adapted to mount different types of jackets without resorting to the use of matched threads and to' provide means on the trunnion block for locking the selected jacket in a predetermined position.

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming-a part of this specification.

A practical embodiment of the invention is illustrated in the accompanying drawing, wherein:

Fig. 1 is a longitudinal sectional view of a. machine gun showing the mounting of a water jacket.

Fig. 2 is a similar view showing the mounting of a jacket constituting a trunnion adapter for aircraft guns.

Fig. 3 is a similar view showing the mounting of a jacket constituting a support for a heavy air-cooled barrel.

The machine gun illustrated in the drawing is of the Browning type and comprises a receiver unit including a trunnion block A that is the same in Figs. 1, 2, and 3. The block has a cen-' tral part 5 forming the front end of the receiver, a conventional rearwardly extending part 6 for receiving the breech end of the barrel B and a forwardly extending cylindrical part I which is externally threaded for mounting the difierent types of jackets, namely the water jacket C of Fig. 1, the jacket D of Fig. 2 serving as a trunnion adapter for aircraft guns, and the jacket E of Fig. 3 serving as the support for the heavy, air cooled barrel used in anti-tank guns. The jackets C, D, and E are respectively provided with trunnions c, d, and e.

The under side of the central part 5 of the trunnion block is formed with a longitudinally disposed chamber 8 for receiving a plunger 9 and a plunger spring I 0 which is confined between the base of the chamber and a collar l l on the plunger and normally causes the plunger to project beyond the front face of the central part 5. The rear portion of the plunger extends through a passage l2 and into a slot l3 in the trunnion ;block so that it may be grasped and retracted jacket E. These recesses have a definite angular relation with respect to the trunnions of their respective jackets so that the trunnions will have the proper angular position when their jacket is engaged by the plunger 9.

In order that it will not be necessary to provide matched threads on the part I of the trunnion block or on the jackets, the final assembly position of the jacket is arranged so that there will be aspace between the rear face of the jackets and the front face of the part i. This space is filled in by a shim, respectively designated I'll8, and i9 for the jackets C, D, and E.

The selection of a shim of correct thickness is made during the original assembly at the'place 20 of manufacture from a series of twelve shims of slightly varying thickness and having reference numbers from 1 to 12. The reference number of the selected shim of correct thickness is stamped on the jacket and preferably the three 25 next higher reference numbers are included so that the inscription for example will read 3-6, meaning that the shim whose'reference number is 3 is the correct shim selected at the factory. Four shims accompany the gun so that adjustb ment'may be made when required. The thickness of the shims of the series are in overlapping relation with the thickest shim having a dimension equal to one-half the pitch of the threads.

In Fig. 2, a bushing 20 is placed between the 35 barrel B and the trunnion block and a thin sleeve 2| spaced from the barrel is carried by the bushing, but these elements do not affect the mounting of the jacket D.

I claim. 40

1 In a machine gun, a block having a projecting tubular part with external threads, a jacket having unmatched threads engaging the threads of the tubular part, trunnions on the jacket, said jacket provided with a recess having a predetermined positional relation with respect to the trunnion, a plunger carried by the block and engaging the recess of the jacket to lock it against rotation with the trunnions in correct final assembly positions, and a shim between the end of the jacket and the block, said shim having a thickness determined by test assembly to compensate for clearance due to the use of unmatched threads on the jacket.

2. In a machine gun, a block having a projecting tubnlar part with external threads, a jacket having unmatched threads engaging the threads of the tubular part, said jacket provided with a recess, a. plunger carried by the block and engaging the recess of the jacket to lock it against rotation in a correct flnal assembly position, and

a shim between the end of the jacket and the "block, said shim having a thickness determined SAMUEL G. GREEN. 

